Strong Activation of Retroviral LTRs in HCC
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ABSTRACT: The ncRNA transcriptome of human hepatocellular carcinoma (HCC) is largely unexplored. We used CAGE to characterize transcription start sites across different etiologies of human HCCs with emphasis on ncRNAs. Here we report that retroviral LTR promoters, expressed in healthy tissues such as testis and placenta but not liver, are widely activated in HCC. Despite HCC heterogeneity, a subset of LTR-derived ncRNAs were more than 10-fold up-regulated in the vast majority of samples. HCCs with a high LTR activity mostly had a viral etiology, were less differentiated and showed higher risk of recurrence. CAGE enabled us to build a promoter map for HCC, which uncovers a new layer of complexity in HCC genomics.
SECONDARY ACCESSION(S): PRJNA278792PRJNA278791
REPOSITORIES: dbGaP
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Project description:An increasing number of non-coding RNAs (ncRNAs) are implicated in various human diseases including cancer; however ncRNA transcriptome of hepatocellular carcinoma (HCC) remains largely unexplored. We use CAGE (Cap Analysis of Gene Expression) to comprehensively map transcription start sites (TSSs) across different etiologies of human HCC as well as mouse HCC, with particular emphasis on ncRNAs distant from protein-coding genes. We find thousands of significantly up-regulated distal ncRNAs in HCC tumors compared to their matched non-tumors, which are as many as protein-coding genes. Moreover, we identify many LTR retroviral promoters activated in HCC tissues and expressed in a subfamily-specific manner, which account for approximately 20% of the up-regulated distal ncRNAs. The transcripts derived from LTRs, determined by 3' RACE, are multi-exon nuclear ncRNAs typically 0.5-2kb in length. This study sheds light on ncRNA transcriptome of human and mouse HCC. Expression profiles using CAGE for 37 mouse HCC. The human data are archived at dbGaP (phs000885.v1.p1). An umbrella BioProject has been created to associate the GEO and dbGaP BioProjects: PRJNA278792
2015-09-10 | E-GEOD-60982 | biostudies-arrayexpress
Project description:An increasing number of non-coding RNAs (ncRNAs) are implicated in various human diseases including cancer; however ncRNA transcriptome of hepatocellular carcinoma (HCC) remains largely unexplored. We use CAGE (Cap Analysis of Gene Expression) to comprehensively map transcription start sites (TSSs) across different etiologies of human HCC as well as mouse HCC, with particular emphasis on ncRNAs distant from protein-coding genes. We find thousands of significantly up-regulated distal ncRNAs in HCC tumors compared to their matched non-tumors, which are as many as protein-coding genes. Moreover, we identify many LTR retroviral promoters activated in HCC tissues and expressed in a subfamily-specific manner, which account for approximately 20% of the up-regulated distal ncRNAs. The transcripts derived from LTRs, determined by 3' RACE, are multi-exon nuclear ncRNAs typically 0.5-2kb in length. This study sheds light on ncRNA transcriptome of human and mouse HCC.
2015-09-10 | GSE60982 | GEO
Project description:Hepatocellular carcinoma (HCC) is one of the most common and lethal cancers worldwide and has a poor prognosis. Promoters represent an essential regulatory element of gene transcription in the human genome. In order to understand the promoter methylation in relation with gene transcription in HCCs, we applied a liquid hybridization capture-based bisulfite sequencing (LHC-BS) approach to examine the promoter methylome of HCCs, for which we customized 150,407 capture probes and enabled coverage of 91.8% of the RefSeq gene promoters within the human genome. We found the differential promoter DNA methylation between HCCs and peripheral normal tissues. Then we integrated promoter methylomic and transcriptomic profiling and described gene expression and regulation in HCCs. Lastly, we validated the key genes in a larger number of samples and screened candidate genes aberrantly regulated by DNA methylation in human HCCs. Capture-based whole genome promoter bisulfite-seq for 8 pairs of HCC tumor and non-tumor liver (NTL) samples.
2014-07-01 | E-GEOD-55752 | biostudies-arrayexpress
Project description:As genome-scale DNA methylation sequencing technologies have improved it has become apparent that tissue-specific methylation can occur not only at promoters, enhancers, and CpG islands but also over larger genomic regions. In most human tissues, the vast majority of the genome is highly methylated (>70%). However, genomic sequencing of bisulfite-treated DNA (MethylC-seq) has revealed large partially methylated domains (PMDs) in some human cell lines. However, to date only cultured cells and some cancers have shown evidence for PMDs, suggesting that PMDs may not be observed in normal human tissues. Here we performed MethylC-seq in a set of human tissues and found that full-term human placenta shows clear evidence of PMDs. Examination of gene expression in human placenta using RNA-seq, with one biological replicate (taken from same placenta)
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2013-03-28 | E-GEOD-39775 | biostudies-arrayexpress
Project description:In most mammalian species, a critical step of placental development is the fusion of trophoblast cell into a multinucleated syncytiotrophoblast layer, which separates the fetal and maternal blood circulations. Advancement in understanding this process came from the identification of two pairs of envelope genes of retroviral origin, independently acquired by the human (syncytin-1 and M-^V2) and mouse (syncytin-A and M-^VB) genomes, specifically expressed in the placenta and with in vitro cell-cell fusion activity. We previously showed that syncytin-A is involved in the formation of one of the two syncytiotrophoblast layer of the mouse placenta -ST-I , facing the maternal lacuna- with syncytin-A null embryos dying at mid-gestation, and their placenta disclosing impaired formation of the ST-I layer. Here by generating syncytin-B KO mice, we demonstrated that syncytin-B null placenta have defects in formation of the syncytiotrophoblast layer-II facing the fetal blood vessels, with refined electron microscopy analyses showing evidence of unfused apposed cells. Lack of trophoblast fusion is associated with signs of trophoblast degeneration and with formation of huge maternal blood lacuna, ultimately disrupting the architecture of the labyrinth layer. These alterations did not result in complete abortion of syncytin-B null embryos, at variance with the syncytin-A KO phenotype, but in a reduced proportion of homozygous syncytin-B knockout individuals at birth, with evidence of late-onset embryonic growth retardation. Double knockout mice experiments demonstrate a premature death of syncytin-A null embryos if syncytin-B is deleted, thus strongly suggesting cooperative involvement of both syncytiotrophoblast layer-I and layer-II for the structural and functional integrity of the maternofetal interface and exchanges. Finally, a microarray analysis of wild-type and syncytin-B null placenta transcripts disclosed alterations in gene expression level for only a very limited number of genes, with the largest change (a 7-fold induction in the syncytin-B null placenta) observed for the connexin-30 gene. Immunohistochemistry further localized the connexin-30 protein in the labyrinth zone of mutant placenta, at the level of the fetomaternal interface. It is proposed that this might correspond to a compensatory process whereby disruption of syncytialization in syncytin-B knockout placenta is counteracted by an enhanced, gap junction mediated, cell-cell communication. These data demonstrate that syncytin-B is required for ST-II syncytial differentiation and the functional integrity of the labyrinth. Altogether, these findings definitively demonstrate that the two endogenous retroviral syncytin-A and -B Env genes contribute independently to the formation of the two syncytiotrophoblast layers during placenta formation, and provide additional insights into the subtle mechanisms of syncytiotrophoblast differentiation in the mouse. Experimental design: Placenta RNA of embryos homozygous for the syncytin-B deletion (SynB-/-) were compared to placental RNA of wild-type embryos (SynB+/+) of the same litter. Two stages of gestation, day 12 and d14, were analyzed. At day 12, 3 litters were obtained; for two of them, the RNAs were analyzed individually, and for the third one, placenta RNAs of the wild-type genotype were pooled. At day 14, one litter was obtained; RNA samples with the same genotype were pooled
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Project description:Hepatocellular carcinoma (HCC) is one of the most common and lethal cancers worldwide and has a poor prognosis. Promoters represent an essential regulatory element of gene transcription in human genome. In order to understand the promoter methylation in relation with gene transcription in HCCs, We applied a liquid hybridization capture-based bisulfite sequencing (LHC-BS) approach to examine the promoter methylome of HCCs, for which we customized 150,407 capture probes and enabled coverage of 91.8% of the RefSeq gene promoters within human genome. We found the differential promoter DNA methylation between HCCs and peripheral normal tissues. Then we integrated promoter methylomic and transcriptomic profiling and described gene expression and regulation in HCCs. Lastly, We validated the key genes in larger number of samples and screened candidate genes aberrantly regulated by DNA methylation in human HCCs.
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Project description:The reversible and dynamic O-GlcNAcylation regulates vast networks of highly coordinated cellular and nuclear processes. Despite the dysregulation of the sole enzyme O-GlcNAc transferase (OGT), is showed to associated with the progression of hepatocellular carcinoma (HCC), the mechanisms by which OGT controls the cis-regulatory elements in the genome and achieves transcriptional functions remain unclear. Here, we demonstrate that the elevated OGT increases HCC proliferation and metastasis by orchestrating the transcription of numerous malignant regulators in vitro and in vivo. Diverse transcriptional regulators are recruited by OGT in HCC cells with progressive malignancy, which shapes the genome-wide OGT chromatin cis-elements occupation. Further, an unrecognized cooperation between ZNF263 and OGT is crucial for activating downstream transcriptomics. We reveal that the O-GlcNAcylation site Ser662 is responsible for ZNF263 chromatin association at candidate gene promoters and OGT facilitated HCC the malignant phenotypes. Our data establish the importance of aberrant OGT and ZNF263 O-GlcNAcylation in HCC malignant progression, and represents the pursuit of OGT as a target for HCC therapy.
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2021-09-09 | PXD020763 | Pride